Impact-tool.



V Patented Dec.

No. 687,85l. J. B. RHODES.

IMPACT TOOL.

(Application filed NOV. 5, 1897.)

(No Modal.)

NITE-D STATES JAY I RHODES, OF CHICAGO, ILLINOIS, ASSIGNOR TO FREDERICK C. AUSTIN, OF CHICAGO, ILLINOIS.

IM PACT-TOO L.

SPECIFICATION forming part of Letters Patent N 0. 687,851, dated December 3, 1901.

Application filed November 5, 1897. derial No. 657,480. (No model.)

To aZZ whom, it may concern:

Be it known that I, JAY B. RHODES, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Impact-Tools, of which the following is a specification.

My invention relates to impact-tools of that class in which a reciprocating piston-hammer operated by fluid pressure 'such as compressed air, steam, or analogous elastic fluidpressureis arranged to work within a toolholding casing having inlet and outlet or exhaust ports and adapted to strike against the butt-end of a tool connected with one end of i the casing.

Objects of my invention are to permit the force of the blow of the piston-hammer against the tool to be varied at will, and thereby regulated in accordance with the character of the work; to relieve an operator working with the impact-tool from objectionable shocks or jars; to provide a compact, simplified, and economical construction; to operate the pistonhammer with great rapidity; to decrease wear and avoid injury to the casingin a simple and effective way, and to provide certain details serving to generallyincrease the utility and efficiency of impact-tools.

In an impact-tool characterized by my invention and securing the foregoing-mentioned ends and advantages the tool-holding casing has a sliding connection with the tool employed and contains a reciprocating pistonhammer which is advanced or moved toward and retracted or moved away from the tool by direct fluid-pressure and during the concluding portion of its back stroke cushioned by and against the direct fluid-pressure, so as to avoid objectionable 'shock to the operator. Provision is also made whereby the pistonhammer may at the concluding or terminal portion of its forward stroke be met and opposed by an elastic resistance proportional to the extent to which the butt-end of the tool extends within the piston-hammer chamber and provided by direct fluid pressure admitted to form an elastic cushion. The piston-hammer on its forward stroke may be met by such elastic cushion prior to or at the time when it strikes the tool, according to the extent to which the latter extends within the piston-hammer chamber, whereby the force of the blow against the tool will be varied in accordance with the extent to which the pistonhammer is thus cushioned.

To the attainment of the foregoing matters or ends the bore which forms the piston-hammer chamber is comparatively short and contains a single reciprocating member which provides'the piston-hammer and which has a comparatively short but rapid stroke, a'portion of which is due to momentum acquired as follows, to Wit: The initial movement of the piston-hammer each way is due to the action of direct fluid-pressure; but beforethe termination of its required stroke it is momentarily subject to the action of direct pres sure at one end and simultaneously opposed by direct pressure at its opposite end, after which juncture the direct pressure primarily applied at one end of the piston-hammer asa means for moving the same is cut off, whereby the terminal portion of its stroke is attained by acquired momentum and is made against a cushion provided by direct fluid-pressure, which upon the termination of the stroke acts to start the'piston-hammer in a reverse direction.

In the accompanying drawings, Figure 1 represents in side elevation an impact-tool understood to embody the principles of my invention. Fig. 2 is a longitudinal central section of such impact-tool, the tool proper and a man ually-controlled valve device being shown in elevation. Fig. 3 is a section through the impact-tool on line so 00 in Fig. 2. Fig. 4 is a like section on 'line y y in Fig. 2. Fig. 5 is an enlarged perspective view of an adjustable set-screw employed in connection with The casing is also provided with a longitudinally-extending bore, which forms a chamber 1 for the piston-hammer, and as a preferred arrangement the bore extends through one end of the casing and is closed at such end by a removable plug D. \Vith such construction the plug is centrally bored to provide a bearing for the stem or butt-end portion 2 of the tool and to permit the same to extend within the piston hammer chamber. The stem or butt-end portion 2 of the tool is also of a length to permit it to be variably extended within the piston-hammer chamber in accordance with the character of the work and the degree of force with which it is desired that the piston-hammer shall strike the tool.

The piston hammer chamber preferably contains only a single reciprocating member consisting of a piston-hammer E, which during operation may move substantially from end to end of the piston-hammer chamber.

As a simple and preferred way of supplying fluid-pressure to certain supply ports or ducts which connect with opposite ends of the piston-hammer chamber the piston-hammer has an annular grooved middle portion adapted to provide fluid pressure space, which receives fluid-pressure from the source of supply and delivers the same to ports or ducts respectively arranged to connect with opposite ends of the piston-hammer chamber. By such arrangement the piston-hammer can be made solid and all weakening thereof by boring it to form ports or ducts can be avoided. During operation the fluid-pressure space thus provided by annularly grooving the middle portion of the piston-hammer is in constant communication with the source of fluidpressure supply whether such space or cham her be formed by a couple of adjacent grooves or by a single groove 3 in constant com munication with the source of supplyfor example, by way of an inlet-port 4: through one side of the casing-it being observed that with such arrangement the constant pressure-supply space within the piston-hammer chamber I is in effect a continuation of the port orduct i.

Fluid-pressure is alternately delivered to opposite ends of the piston-hammer chamber from the constant fluid-pressure space which is thus formed within the piston hammer chamber by grooving the piston-hammer. To permit such delivery of fluid-pressure to the ends of the piston-hammer chamber, the easing is provided with a couple of longitudinally-extending ports or ducts 5 and 6, having their end portions deflected laterally toward the piston-hammer chamber and connected therewith. These supply ports or ducts respectively lead from points at opposite sides of and adjacent to the middle of the piston-hammer chamber and extend to and connect with such chamber at its ends.

Fluid-pressure is alternately delivered to the ports 5 and 6 from the constant-fluid pressure space in the piston-hammer chamber as a means for startingand drivingthe piston-hammer toward and away from the tool. Fluid- 5 and 6 from the constant fluid-pressure space pressure is also alternately delivered to ports within the chamber at times to permit such fluid-pressure to provide elastic cushions within the end portions of the piston-hammer chamber in opposition to the moving piston, which serves to alternately open and close exhaustor outlets ports 7 and Sin the casing with reference to the foregoing-described twofold use of the direct fluid-pressure. As an exceedingly simple and highly effective arrangement the piston-hammer is grooved or recessed, as hereinbefore set forth, so as to alternately open and close the fluid-pressuresupply ducts 5 and 6 and also to permit the constant fluid-pressure space or chamber formed by such groove or recess to commence the delivery of fluid-pressure to each of said d ucts ahead of the piston-hammer--that is to say, before the moving piston-hammer has reached the end of the piston-hammer cylinder adjacent to the delivery end of the duct to which fluid-pressure is thus admitted from the constant fluid-pressure space. For example, when the piston-hammer has nearly reached the point where it will strike the tool, asin Fig. 2, the liuid-pressure-supply port 6 will be closed by the piston,while corresponding port 5 will be open to the constant fluidpressure space. At such juncture the exhaust-ports, which are arranged between the middle and ends of the piston-hammer cylinder, will be closed. A slight continuation, however, of the forward movement of the piston-hammer will permit it to strike the tool and also open the exhaust or outlet port 8. This delivery of direct fluid-pressure to the forward end of the piston-hammer cylinder ahead of the piston-hammer will serve to provide an elastic cushion between the forward end of the piston-hammer and the opposing end of the piston-hammer cylinder and will oppose the terminal portion of the stroke of the piston-hammer to adegree proportional to the extent to which the stem or butt-end portion of the tool projects within the piston hammer cylinder, and thereby proportionally vary the force of the blow. Thus, for example, when the tool is resting upon the work and the casing is raised by the operator so as to cause the butt-end of the tool to project within the piston-hammer cylinder to an extent considerably less than shown in Fig. 2 the forwardly-moving piston-hammer will be opposed by direct fluidpressure delivered from port 5 before it has reached the tool, whereby a much lighter blow will be delivered. By such arrangement the force of the blow can be reduced to any desired extent. On the other hand, when the piston-hammer is driven in a direction away from the tool by the action of fluidpressure delivered through fluid-pressure-supply port 5 it will close exhaust-port 8 and open exhaust-port 7 and also close said port 5 and open the corrcspondin g port 6 in time to permit the latter to deliver fluid-pressure from the constant fluid-pressure space or chamber to the rear or back end portion of the pistonhammer chamber before the piston-hammer has completed its stroke. In this way the terminal portion of the stroke of the pistonhammer in a direction away from the tool Willbe opposed by direct fluid-pressu re, which will serve to cushion the piston-hammer, and thereby prevent shock.

With the arrangement of constant fluidpressure space or chamber and ports 5 and 6 (illustrated in Fig. 2) the piston-hammer may be said to operate as a momentum pistonhammer. When, for example, port 6 is closed and port 5 is open to the constant fluid-pressure space or source of direct pressure, fluid-pressure delivered through port5 will drive the piston-hammer in a direction away from the tool. Prior to reaching the terminal portion of its stroke and before closing port 5 the movement of the pistonhammer will permit the constant fluid-pressure chamber or source of direct supply to communicate with both of the ports or ducts 5 and 6, whereby there will be to some extent a temporary counterbalancing pressure at opposite ends of the piston-hammer, and when by further movement on the part of the piston-hammer it has closed the port or duct 5 it will be met by direct pressure delivered through the port or duct 6. When, however,the direct pressure which has served to drive the piston-hammer away from one end of the piston-hammer chamber is cut 0% or has ceased to become efiective as a propelling agent, the piston-hammer will have acquired sufficient momentum to cause it to complete its stroke and to also compress the elastic cushion against whichiti's thus moved, and while the piston-hammer may in this way strike the tool with a degree of force proportional to the momentum which it has thus acquired as a result of the initial direct fluid-pressure its comparatively short stroke and quick action will permit it to do all necessary and desired work within a given time.

The sliding connection between the tool and the casing permits a slight leak, in which way there will be no liability of the pistonhammer stopping on a dead center when fluid-pressure is cut off from the inlet-port 4 by a manually-controlled valve herein employed as a means for letting on and cutting off the supply of fluid-pressure.

The casing, which serves as atool-holder, is provided with a supply-valve F, arranged to work within a chamber 9 alongside the piston-hammer chamber and adapted for opening and closing the contracted receiving end of the inlet-port 4. This supply-valve is normally in position to close the inlet-port and is subject to a lever G, which is pivotally supported between its ends upon the casing, as at 10, and arranged within an oblong slot or opening 11, which is formed through the handle B of the casing and extended transversely to the length of the latter. One end of the lever engages the valve, while its opposite end is desirably adaptedto be engaged by a finger of the hand of the operator grasping the handle B, a convenient form being a part ring or ring 12, arranged at one end of the lever and adapted to receive the finger ofthe operator.

The valve-chamber 9 can consist simply of a longitudinallyextending bore and the valve can consist simply of a stem provided at each end with a head fitted to work in the bore which forms the valve-chamber. With such arrangement the lever can engage the head at one end of the valve-stem, while the head at the opposite end of such stem can serve to open and close and also to vary the area of the receiving end of the inlet-port 4. The valve-chamber thus arranged has a supply-inlet 13, arranged to communicate with a supply-duct 14, which latter can beconnected by any suitable connection, such as a flexible pipe, with a source of fluid-pressure supply. The valve is practically adjustable and is preferably subject to a spring H,arranged to normally maintain the valve in position to close the inlet-port 4 of the pistonhammer chamber. The spring H is backed by an adjustable stop I, arranged to slide within one end portion of the bore 9, which forms the valve-chamber, and held against rotation in any suitable way-for example, by one or more splines 15 on the stop fitted to slide in grooves in the inner wall of the bore 9. The stop is in turn backed by an adjustable threaded plug or set-screw K, fitted to work in a threaded portion 16 of the bore 9 and held against accidental turning by corrugating the abutting ends of both set-screw and stop, so that while the set-screw can be turned independently of the stop for the purto an extent to allow it to only partiallyopen the receiving end of port 4. As a simple and further desirable arrangement the bore or valve-chamber 9 can be formed by first boring the casing and then fitting a cylindric shell 18 Within such bore, the shell in such case being provided with lateral openings communicating with the ports or ductset and 14 and forming portions thereof, substantially as illustrated in Fig. 2, wherein the port 4 is enlarged, so as to provide about the shell 18 an annular port-space communicatingwith the valve-chamber by way of a conple of small openings in the shell, and like wise the port or duct 14 is adapted to provide about the shell an annular port-space which communicates with the valve-chamber by way of a couple of small openings. By such arrangement the body of the tool-holder and the handle therefor can be made in one piece and also cast with a lateral extension 19, which is bored to receive the shell which provides the bore or valve-chamber 9.

The plug or bearing D at one end of the casing can be conveniently held in connection therewith by an annular screw-cap L, which is screwed upon the externally-threaded end of the casing, so as to clamp an annular flange 20 on the plug against the end of the casing. To prevent such cap from accidentally working loose, the inner annular edge of the cap can be corrugated, as at 21, and the plug can be provided with a spring tooth or stop 22, arranged to engage such corrugated edge portion of the cap and while holding the latter against accidental turning permit it to be manually turned when so desired.

What I claim as my invention is I 1. An impact-tool comprising a tool-holding casing having a sliding connection with thetool employed and provided with a piston-hammer chamber; a reciprocating piston-hammer having its middle portion recessed to afford constant fluid-pressure space; an inlet-port in communication with such constant fluid-pressure regardless of the position of the piston-hammer; exhaust-ports which are opened and closed by the pistonhammer; and longitudinally-extending ports or ducts which lead from the middle portion of the piston-hammer chamber to the ends thereof, and which are alternately opened and closed by the piston-hammer so as to alternately take fluid-pressure from the constant pressure-space aiforded by recessing the piston-hammer, and which are at intermediate intervals simultaneously in open communication with the constant fluid-pressure space, the latter being of suflicient width to momentarily deliver fluid-pressure to both ducts at a time between the initial and terminal portions of the stroke of the pistonhammer which is first actuated by direct pressure at one of its ends, then subject to direct pressure at both ends, and thereupon carried by momentum against a cushion provided by direct pressure, substantially as described.

2. An impact-tool comprising a tool-holdingcasing containing a piston-hammer chamber and provided with an inlet-portet opening at the middle portion of the piston-hammer chamber, and ducts 5 and 6leading from the middle portion of the piston-hammer chamber to the ends thereof; a tool having asliding connection with the tool-holding casing and provided with a shank or stem which can be variably extended within the piston-hammer chamber so as to vary the moment at which it is struck by the piston-hammer; a reciprocating piston-hammer E having a recess 3 of a width to register with both of the JAY B. RHODES.

\Vitnesses:

A. F. DURAND, MARGARET M. WAGNER. 

